In Alien Bikini, a young girl is attacked by street thugs, only to be saved by the city's main superhero — the Protector, whose main disguise is a comedy mustache. But when he takes her home to his lair, she tries to seduce him — because she's actually an alien who feeds on the sperm of human males. Unfortunately, the superhero has taken a vow of chastity and is unable to hook up with any women, alien or otherwise.
In the clip above, witness the totally gross thing that happens when he rebuffs the "Alien Bikini" in the middle of their make-out session.
Here's the trailer for Invasion of Alien Bikini, quite possibly Korea's greatest contribution to the "alien bikini" subgenre: